As most of you know by now, I am hosting a World Oceans Day.   Beyond Eocene lake fish I am pretty ignorant. SOOOO this is a learning experience for me as well.   I know people use a serration per mm count to ID dinosaur teeth that are closely related.   Can this be done for shark teeth? because to me, a lot of them look similar.   Are there any other teeth out there that we can use a serration per mm count to ID?